Grounding; Motor Selection - Toshiba VFS5 Series Operation Manual

Selection of Main Circuit Wiring Equipment and Standard Cable Sizes (cont'd)
Notes:
1.) Contacts used to connect drive terminals should be capable of switching low current
signals (i.e. 5 mA).
2.) The drive has internal motor overload protection which has been functionally certified by
Underwriters Laboratories Inc. and no additional external motor overload protection is required
when used to drive a single motor load (see 1996 NEC Article 430-32 and 430-39).
3.) When wiring with parallel conductors, the conductors should be kept together in phase sets to
avoid heating the surrounding metal by induction. Install U1, V1, W1 conductors in one conduit
and parallel conductors U2, V2, W2 in another conduit. The ground conductor must be run in the
same conduit. See 1996 NEC Article 300-20(a), 310-4, 310-5. Size the grounding conductor in
accordance with 1996 NEC Table 250-95.
4) Twisted pair wires should be used for external meters connected to AM and FM terminals.
5) For multiple motor applications, a thermal-magnetic circuit breaker must be installed between
the drive and each motor (even though the drive has has built-in overload protection). The thermal
circuit is for overload sensing and the magnetic coil is for abnormal conditions such as short circuits.
Select the MCCB (molded case circuit breaker) in accordance with 1996 NEC Article 430-51 through
430-53, 430-152, and 240-6.
The drive must be grounded in accordance with Article 250 of the National Electrical Code or Section 10
of the Canadian Electrical Code, Part I and the grounding conductor should be sized in accordance with
1996 NEC Table 250-95 or CEC, Part I Table 16. See Installation Safety Precautions notes 7 and 14.
C A U T I O N
1) Exceeding the peak voltage rating or the rise time allowable of the motor insulation system will
reduce the life expectancy. To insure good motor insulation life, consult with the motor supplier to
determine motor insulation ratings and allowable maximum output lead distance. Long lead lengths
between the motor and the drive may require filters to be added to the drive output.
Suggested Maximum Output Lead Distance
AC Motor
Voltage
575 V
1
For lead lengths that exceed suggested maximum contact your local distributor or Toshiba for
additional application assistance.
2
Toshiba EQP III, III-XS & EQP III-841 motors incorporate an insulation system that is in
compliance with NEMA MG-1-1998 Section IV Part 31.
2) Bearing Considerations:
Motors operating from adjustable speed drive power sources tend to operate at higher
temperatures which may increase the need for more frequent lubrication cycles.
TOSHIBA

Grounding

Conduit is not a suitable ground for the inverter.

Motor Selection

1
PWM Carrier
Frequency
< = 5 kHz
> 5 kHz
17
NEMA MG-1-1998 Section IV
Part 31 Compliant Motors
200 ft.
100 ft.
2